Magnetic resonance imaging with fat-water signal separation
AssigneeThe Board of Trustees of the Leland Stanford Junior University
InventorsScott B. Reeder, Norbert J. Pelc
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Abstract
A generalized multi-point fat-water separation process is combined with steady-state free precession (SSFP) to obtain high quality images of articular cartilage with reduced imaging time.
Claims18
A method of obtaining magnetic resonance images with signal separation for two species comprising the steps of:
- a) obtaining first magnetic resonance signals from an object having first and second species using a first repetition time and a first echo time,
- b) obtaining at least second magnetic resonance signals from the object using a second echo time, in a second sequence wherein tip angle, α, for each magnetic resonance sequence is given by:
- α
- =
- cos
- -
- 1
-
- (
- e
- -
- TR
- T
- 1
- -
- e
- -
- TR
- T
- 2
- 1
- -
- e
- -
- TR
- T
- 1
-
- e
- -
- TR
- T
- 2
- )
- where T1, T2 are relaxation times of material in the object and TR is the sequence repetition time, and
- c) combining the magnetic resonance signals from steps a) and b) to obtain a first species signal and a second species signal which match said magnetic resonance signals in a least squares sense.
A method of obtaining magnetic resonance images with signal separation for two species comprising the steps of:
- a) obtaining first magnetic resonance signals from an object having first and second species using a first repetition time and a first echo time,
- b) obtaining at least second magnetic resonance signals from the object using a second echo time, wherein the relative phase between the two species signals changes by Δφ, when Δφ is not an integer multiple of 180 degrees, and
- c) combining the magnetic resonance signals from steps a) and b) to obtain a first species signal and a second species signal which match said magnetic resonance signals in a least squares sense.
In a magnetic resonance imaging system, a processor which is programmed to:
- a) obtain first magnetic resonance signals from an object having two species using a first repetition time and a first echo time,
- b) obtain at least second magnetic resonance signals from the object using a second echo time, wherein the relative phase between the two species signals changes by Δφ, when Δφ is not an integer multiple of 180 degrees, and
- c) combine the magnetic resonance signals from steps a) and b) to obtain a water signal and a fat signal.
A method of obtaining magnetic resonance images with signal separation for two species comprising the steps of:
- a) obtaining first magnetic resonance signals from an object having first and second species using a first repetition time and a first echo time,
- b) obtaining at least second magnetic resonance signals from the object using a second echo time, wherein the relative phase between the two species signals changes by Δφ, when Δφ is not an integer multiple of 180 degrees,
- c) combining the magnetic resonance signals from steps a) and b) to derive a magnetic field map, and
- d) using the signals from steps a) and b) and the magnetic field map from step c) to obtain a fat signal or a water signal.
Dependencies are inferred from the claim text.